Summary: Highly optimized tight-binding model of silicon
Thomas J. Lenosky, Joel D. Kress, Inhee Kwon, and Arthur F. Voter
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
Byard Edwards
Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501
David F. Richards, Sang Yang, and James B. Adams
Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Received 23 April 1996; revised manuscript received 20 September 1996
We have fit an orthogonal tight-binding model of silicon with a minimal (s,p) basis and a repulsive pair
potential. The pair potential and the tight-binding matrix elements are represented as cubic splines with a
5.24-Ć fixed radial cutoff in order to allow maximum flexibility. Using a numerical procedure, the spline
parameters were fit to simultaneously optimize agreement with ab initio force and energy data on clusters,
liquid, and amorphous systems as well as experimental elastic constants, phonon frequencies, and Grušneisen
parameter values. Many such fits were performed to obtain a potential that we judged to be optimal, within the
implicit limitations of our potential form. The resulting optimized potential describes many properties very
accurately and should be a useful model given its relative simplicity and speed. Our fitting method is not
difficult to apply and should be applicable to many other systems. S0163-1829 97 00604-8
I. INTRODUCTION
Silicon is a material that has great economic and techno-
logical importance. As a result, a great deal of scientific ef-